These experiments are designed to investigate changes in processing of nuclear RNA which occur during induction of colon cancer in mice by 1,2-dimethylhydrazine. The correct processing, or selection, of mRNA molecules from the pool of nuclear precursors is an important aspect of normal differentiation and development, and there is suggestive evidence that processing is aberrant during carcinogenesis in the liver. Further, a general disruption in the fidelity of processing could give rise to the many other, seemingly unrelated, biochemical changes seen in transformed cells. The specific objectives are to investigate whether RNA sequences synthesized in the normal colon but usually restricted to the nucleus are instead found as cytoplasmic species, and to investigate whether alkylation of RNA by dimethyl-hydrazine contributes to defective processing.